HVLP - Getting splatter - Need help

[tryme96z]

I am having splatter issues with a my new Astro Pneumatic EuroPro HVLP gun and am looking for advice.

When spraying Emtech (Water based pigmented "lacquer") I am getting what appears to be decent atomization, but every 1'-2' I get a couple small splats of material. It is very consistent in that it does happen enough that I could not apply a final coat of material if I wanted to.

I have done some thinning of the material per the manufacture's instructions of starting at 5% and it helped somewhat. But it did not completely solve the problem. I want to be careful how much water I am adding to the product as I am spraying on wood and do not want to increase and potential to raise grain.

On top of this the manufacture tells me I should be able to shoot the product right out of the can without thinning as the product was designed for HVLP use.

Having spent my day yesterday testing psi, adding/removing things to impact CFM (including a different smaller compressor to try to increase the splatter problem), thinning, adjusting fan, adjusting material delivery, and changing tip/cap size (1.9mm and 1.3mm)....I am out of ideas of what I could be doing wrong.

Recommendations?


Gun: http://www.astrotools.com/index.php/europro-forged-hvlp-spray-gun-with-1-9mm-nozzle-plastic-cup.html
Tip/cap: 1.9
Compressor: 60 gallon, 12.x CFM @ 90psi
Compressor line: 3/8" rubber hose, 50'
Compressor line connectors: High flow quick adapters
Regulator: 3/8" at the gun. Generic brand.
Water Removal: Have tested with and without a generic disposable at the gun, no difference in spray with/without. (suspected a cfm issue, but appears not to be the case)
Material: Target Coatings Emtech 6500 (https://artdec.ca/en/p/443/em6500-water-based-acrylic-pigmented-lacquer)
Material Specs/Spraying info: 1.8mm - 2mm cap/needle recommended. https://artdec.ca/media/catalog/specs/TC_TechDataSheet_EM6500_R4_kmRjgHx.pdf

 

[Git]

What does your spray pattern look like on a piece of paper? Your looking for a nice elliptical pattern with tapered edges

 

[tryme96z]

Far right in the photo. It is a "good" pattern.

 

[never enuf time]

Splatter could be dirty gun or unfiltered product coming out of gun. If those bases are covered try thinning more see what happens.

How is the water based lacquer cover for you ? I use shellac based primer on wood. It works well but is harder to spray.

 

[bodyguy16]

I beleive the problem to be in atomization, 1.9 is a pretty big nozzle size for base coat and clear coats. It's generally a primer size nozzle, that being said try to turn down the material screw and see from there.

Sent from my SM-G903W using Tapatalk

 

[tryme96z]

Conditions above are based on gun straight out of the package. No signs of grease or debris.

I did clean the gun last night, so I will go out and run a few more tests with more thinning, material delivery, and a switch back from the 1.9mm to the 1.3mm tip.

Emtech (tinted to a shade of white) has provided great coverage, though I primed the maple wood with Binz first. I love the way the product lays flat and it's burn-in. I completed a set of built-ins a few months ago with it. If I did not like the product so much, I would not be fighting so hard to make it work.

A $15 HF "hvlp" gun with a 1.4mm tip and a 15 gallon Dewalt/Emglo compressor did great for most that project, until the end when I started getting similar splatting that I am getting with the new gun. I did not do any thinning with the HF gun. One factor that did change was ambient air temp by about 10*.

I was unable to diagnose why splatting started with the HF gun/15 gallon compressor combo, but took the action of upgrading the compressor and now gun to help ensure for the next project I can get good results.

 

[never enuf time]

I also use a purple hvlp gun. I had a 1.4 tip & bought a 1.5 by mistake , that turned out to work better for spraying latex enamel ( Benjamin Moore Advanced).

I have clog issues with spraying shellac based primer, so I roll on with baby roller.

I need to get another 1.5 gun & use the old one to spray primer with to speed up the process.

Where did you get the em6500 ? I need to try out another primer ( I've tried out several but they don't dry & sand as well as shellac based).

 

[tryme96z]

I bought the em6500 directly from Target Coatings. Paying $20 shipping is kind of lame for a $40 a gallon product (coupon), but I love the way this product has performed. Oh and it has a 24-month shelf life which is fantastic for a hobbyist.

 

[K13]

Are you keeping the vent hole in the top of the paint cup clear?

 

[pcmeiners]

**** in the paint? did you run everything going into the spray gun though a paint strainer?

 

[Git]

I have sprayed their regular waterborne lacquer and have never had to thin it it or had any problems like you mentioned. (I realize that their pigmented product is going to be a lot thicker)

I agree - I don't like their shipping charges so when I wanted some color, I switched to General Finish Poly which comes in black or white and my local lumberyard carries it for a reasonable price

The tech sheet for EM6500 definitely specs a pretty large needle set and cap:
Compressed Air HVLP - 1.8mm–2.0mm needle set and corresponding air cap.

Are you filtering the lacquer? Is everything tightened up? The cup is full? This may be helpful:
https://www.pittsburghsprayequip.com/2016/02/05/why-your-spray-gun-is-spitting/

Regarding primer - the best I have used is BIN (shellac based) but requires denatured alcohol for cleanup which makes it a bit of a pain to use

 

[dnschmidt]

I have that gun and it's outstanding with automotive materials so I see no reason it wouldn't work for woodworking. You definitely want to use the big tip. You must strain the material. TAKE THE FILTER OUT OF THE BOTTOM OF THE CUP. Thick materials will not go through the little tiny plastic filters that these guns ship with. Also drill out the cap on top of the cup to a larger size since if this clogs up (common problem with waterborne materials) you will not get any flow. Also, if you see any material build up on the wings of the aircap that indicates a problem. Additionally, make sure you nozzle is tight as any air leakage around the nozzle can cause these problems.

MOST IMPORTANTLY. Make sure you are spraying at 29 PSIG with the trigger pulled and air flowing through the gun. Everybody tries to get away with less air pressure than a good gun needs and that causes all sorts of problems. Overspray is a part of spraying life. If you want a good finish you have to deal with it.

 

[tryme96z]

Splatter issue resolved!

I was able to get rid of the splatter I was getting with both tip/cap/needle assemblies and without thinning. The 1.9mm definitely gave a wider fan of material. Thinning helped out a lot with the 1.3mm in achieving a decently wide fan of material.

Not 100% sure which tactic solved the splatting issue (my guess is the tightening), but I performed the following:

- I ensured the gun was clean inside and out (brand new gun, so not really an issue)
- Added the in cup filter (do not have any pour through filters on hand, so used what I had)
- I tightened the nozzle and cap on tighter than I would expect it to need to be. Previously I did tight with caution to the reality of soft metals are at play in these parts.
- Verified the cup’s vent hole was not clogged. It wasn’t.

Side note: Yes I was setting the pressure regulator while air was flowing through the gun. ☺

Thank you for your help.


Resources
- Spraying paint with HVLP guns: http://homesteadfinishingproducts.com/wp-content/uploads/2014/05/paintspraying_ver3.pdf
- Spitting spray gun: https://www.pittsburghsprayequip.com/2016/02/05/why-your-spray-gun-is-spitting/
- Measuring and adjusting viscosity http://finishing.tips/measure-and-adjust-the-viscosity/
- HTVLP Troubleshooting: http://www.portlandcompressor.com/hvlp/trouble-shooting.aspx